Well technically Warhead is right, even according to normal physics it is impossible to completely destroy an immortal core, or anything for that matter, because information must always be preserved, meaning that theoretically I should be able to collect the residual Hawking radiation that used to be the immortal core and regrow it.

I thought that we established a long time ago that the essence of the Immortal Core exists outside of the universe, independent of its physical projections into our spacetime reality. Trying to affect the core from within the universe is like trying to break a movie projector by attacking the projected image. You can collect all the Hawking radiation you want from the projection, but it's not going to give you any access to the projector.

Crack theory: Immortals are the projections of real humans in the brikverse. They will not die as long as their representing human IRL doesn't die. And since humans live a divinely-long time compared to minifigs...

MFS shows off one of the new Maniac shoulder mounted squad support weapons. The Uber-Bastard Cannon. Mortal troops can't do this unaided but there is a wide viriaty of Power Armoured suits that can manage just fine.

It can also be deployed as a static weapon with a tripod for better accuracy.